The Royal Fleet Auxiliary (RFA) is a civilian-manned fleet owned by the United Kingdom's Ministry of Defence and is one of the five fighting arms or branches of the Royal Navy.[1] Its purpose is to support the Royal Navy[2] to maintain operations around the world. Its primary role is to supply the Royal Navy with fuel, ammunition and supplies, normally by replenishment at sea (RAS). It also transports Army and Royal Marine personnel, as well as supporting training exercises, and engaging in anti-piracy, anti-drug smuggling, and humanitarian operations.

The RFA counts an Aviation Training ship/Hospital Ship and landing vessels amongst its assets. RFA personnel are members of the Ministry of Defence civil service, and since 2003, special members of the Royal Naval Reserve deemed sponsored reserves, which are civilians who must be part of the Armed Forces in some capacity, in order to carry out specialist civilian jobs in a military capacity. However the RFA itself is not part of the Naval Service, and officers wear Merchant Navy rank insignia with naval uniforms but are under naval discipline when the vessel is engaged on warlike operations. RFA vessels are commanded and crewed by these civilians, augmented with regular and reserve Royal Navy personnel to perform specialised military functions such as operating and maintaining helicopters or providing hospital facilities. Royal Navy personnel are also needed to operate certain weapons, such as the Phalanx, however other weapons (such as the GPMG or 20mm cannon) are operated by RFA personnel.

The RFA was first established in 1905 to provide coaling ships for the Navy in an era when the change from sail to coal-fired steam engines as the main means of propulsion meant that a network of bases around the world with coaling facilities or a fleet of ships able to supply coal were necessary for a fleet to operate away from its home country. Since the Royal Navy of that era possessed the largest network of bases around the world of any fleet, the RFA at first took a relatively minor role.

The RFA firstly became heavily relied on by the Royal Navy during World War II, when the British fleet was often far from available bases, either due to the enemy capturing such bases, or, in the Pacific, because of the sheer distances involved. World War II also saw naval ships staying at sea for much longer periods than had been the case since the days of sail. Techniques of Replenishment at Sea (RAS) were developed. The auxiliary fleet comprised a diverse collection, with not only RFA ships, but also commissioned warships and merchantmen as well. The need for the fleet to be maintained was unambiguously demonstrated by World War II.

After 1945, the RFA became the Royal Navy's main source of support in the many conflicts that the Navy was involved in. The RFA performed important service to the Far East Fleet off Korea from 1950 until 1953, when sustained carrier operations were again mounted in Pacific waters. During the extended operations of the Konfrontasi in the 1960s, the RFA was also heavily involved. As the network of British bases overseas shrank during the end of the Empire, the Navy increasingly relied on the RFA to supply its ships during routine deployments.

The most important role provided by the RFA is replenishment at sea (RAS), therefore the mainstay of the current RFA fleet are the replenishment ships.[6] The Wave-class are 'Fleet Tankers', which primarily provide under way refuelling to Royal Navy ships, but can also provide a limited amount of dry cargo. The Rover-class that were decommissioned in 2017 are being replaced by the new Tide-class 'Fast Fleet Tankers' that were ordered in February 2012. The four new tankers have been ordered from DSME, South Korea with design support from Britain's BMT Defence Services, the first of which Tidespring entered service in 2017.[7] The 2015 Strategic Defence and Security Review has confirmed that three "Fleet Solid Support" Ships will be built and bidding for the contract will start in late 2016.[8]

Fort Victoria is a 'one-stop' replenishment ship, capable of providing under way refuelling and dry cargoes (I.e rearming, victualling and spares). The older Fort Rosalie-class ships provide only dry cargoes. The Wave-class, Fort Victoria and the Fort Rosalie-class have generous aviation facilities, providing aviation support and training facilities and significant vertical replenishment capabilities. They are capable of operating and supporting several Merlin and Lynx Wildcat helicopters, both of which are significant weapons platforms. The presence of aviation facilities on RFA ships allows for them to be used as 'force multipliers' for the task groups they support in line with Royal Navy doctrine.

The unique support ship in the fleet is the aviation training ship Argus, a converted roll-on/roll-off (RoRo) container ship. She is tasked with peacetime aviation training and support. On active operations, she becomes the Primary Casualty Receiving Ship (PCRS); essentially a hospital ship. She cannot be described as such - and is not afforded such protection under the Geneva Convention - as she is armed. She can, however, venture into waters too dangerous for a normal hospital ship. Argus completed a refit in May 2007 intended to extend her operational life to 2020.[9]

The Point-class sealift ships were acquired in 2002 under a £1.25bn private finance initiative with Foreland Shipping known as the 'Strategic Sealift Service'. These ships are Merchant Navy vessels leased to the Ministry of Defence as and when needed. Originally six ships were part of the deal, allowing the MoD use of four of the ships with two being made available for commercial charter, these latter two were released from the contract in 2012.[10] The Ministry of Defence also maintains a single commercial tanker under permanent charter, the Maersk Rapier.[11] The ship is tasked with supplying fuel to the United Kingdoms various naval establishments at home and overseas, as well as providing aviation fuel to RAF stations at Cyprus, Ascension and the Falklands.[11] The MoD charters the vessel to commercial companies during periods where she is not in use for defence purposes.[11][12]

As of 2018, there are 11 ships in service (and 2 on trials) with the Royal Fleet Auxiliary with a total displacement of approximately 300,000 tonnes. These figures exclude the five merchant navy vessels under charter to the Ministry of Defence.